A critical review of all the reported structures and powder diffraction patterns in the uranium telluride system has been undertaken. Our recommendations are:

1. Structures that are correct:

• Cubic – UTe: no experimental pattern exists. Retain calculated 15–865.

• Cubic – U3Te4: retain poor quality 12-610 but adopt the pattern calculated here.

• Cubic U2Te3: no experimental pattern exists. Adopt pattern calculated here.

• Orthorhombic UTe2: Adopt the new pattern of Boehme et al.

• Monoclinic αUTe3: Adopt the new pattern of Boehme et al.

• Orthorhombic βUTe3: Adopt the pattern calculated here.

• Orthorhombic UTe5: Adopt the new pattern of Boeheme et al.

2. Structures in need of refinement:

• Orthorhombic U2Te3: Adopt pattern calculated here over 34-807.

• Hexagonal U7Te12: Adopt pattern calculated here but retain 24-1368.

• Orthorhombic UTe1.78: Adopt pattern calculated here and retain our modified 21-1404 reported for U4Te7.

• Orthorhombic UTe2.5: Adopt pattern calculated here.

• Orthorhombic UTe3.4: Accept recent pattern of Boehme et al.

3. Phases for which no structures or reliable patterns exist:

• Orthorhombic U3Te4: no published pattern.

• Tetragonal U3Te5: three patterns 21-1407, 34-766 and 34-896 exist but all are of very poor quality.

4. Phases which probably do not exist:

• Tetragonal UTe1.77

• Tetragonal UTe2

• Cubic UTe2

• U3Te7 (21-1402)

• U3Te8 (21-1406)

To interpret highly superimposed diffraction patterns, the Rietveld method together with conventional X-ray powder diffraction techniques were carried out on a series of heat-treated weldments of cast super duplex stainless steel. High temperature processing of this type of alloys causes embrittlement and loss of corrosion resistance owing to precipitation of intermediate phases, principally sigma-phase. The annealing processing of the samples proceeded at temperatures in the range of 800–950 °C for periods of time from 1 to 96 h. This procedure permitted an accurate quantification of the microstructural components such as austenite, ferrite and sigma-phase in all studied samples. The contents of sigma-phase in the heat-affected zones of all weldments reached asymptotical values of 30–38 wt% after 96 h of heat treatment.

The superconductor related phases Ba3R3Cu6O14+x(or Ba2−zR1+zCu3O7+x, with z=0.5), where R = Pr, Nd, Sm, and Eu, have been prepared and characterized by X-ray powder diffraction, ac magnetic susceptibility measurement, resistivity measurement and thermogravimetric analysis (TGA). Attempts to make corresponding compounds with R = Gd, Dy, Y, Er, and Lu were not successful; they do not appear to form for rare-earth elements, R, with an ionic size smaller than Eu. The oxygen content of the successful materials was estimated by TGA. The Ba3R3Cu6Cu14+xcompounds which were sintered at 950°C and annealed in oxygen at 550°C were found to be nonsuperconducting above 10K. Previously reported results for the R=La compound have indicated that it was superconducting with a transition temperature of 15K The oxidation-reduction behavior of the Ba3R3Cu6O14+xmaterials is similar to that of the superconductor phases Ba2RCu3O6+x.

These present isostructural compounds are tetragonal with a space group of P4/mmm. The cell parameters range from a = 3.8612(4), c = 11.5624(14) Å, V = 172.38(4) Å3in the Eu compound to a = 3.8893(3), c = 11.6370(11) Å, and V = 176.03(3) Å3in the Pr compound. The standard X-ray diffraction patterns of these materials are given.

Crystal structure of compositionally homogeneous, nanocrystalline ZrO2–CeO2 solutions was investigated by X-ray powder diffraction as a function of temperature for compositions between 50 and 65 mol % CeO2. ZrO2-50 and 60 mol % CeO2 solid solutions, which exhibit the t′-form of the tetragonal phase at room temperature, transform into the cubic phase in two steps: t′-to-t″ followed by t″-to-cubic. But the ZrO2-65 mol % CeO2, which exhibits the t″-form, transforms directly to the cubic phase. The results suggest that t′-to-t″ transition is of first order, but t″-to-cubic seems to be of second order.

Phase transformation temperatures of a polycrystalline Ni-rich Ti49.86Ni50.14 shape memory alloy were investigated using a differential scanning calorimeter. In situ structural and texture analyses of the monoclinic Ti49.86Ni50.14 were investigated using neutron powder diffractometer technique. Differential scanning calorimeter results showed that this Ni-rich alloy has a one-step cubic to monoclinic martensitic phase transformation on cooling and a one-step monoclinic to cubic transformation on heating. In situ high-resolution neutron powder diffraction data of the monoclinic phase from low temperatures to room temperature on heating are consistent with the differential scanning calorimeter’s heating results. In addition, the refined monoclinic crystal structure parameters for all neutron diffraction data sets agree satisfactorily with single-crystal X-ray diffraction results. The multiple-data-set capabilities of the GSAS Rietveld refinement program, with a generalized spherical-harmonics description was used successfully to extract the texture description directly from a simultaneous refinement using 52 time-of-flight monoclinic neutron diffraction patterns, taken from a polycrystalline sample held in 13 orientations inside the diffractometer.

The structure of 3,4-diaminopyridin-1-ium dihydrogen phosphate, [C5H3(NH)(NH2)2]+ (H2PO4)−, is solved from conventional X-ray powder diffraction data in direct space (monoclinic unit cell with a = 16.0725(9) Å, b = 7.7301(3) Å, c = 14.6189(9) Å, β = 96.869(1)°, V = 1803.2(2) Å3, Z = 8, and space group I2/c), and optimized by energy minimization in the solid state. In the crystal structure of the title compound, dihydrogenphosphate tetrahedra are linked by strong hydrogen O-H…O bonds forming chains running parallel to the b-axis. Antiparallelly π–π stacked DAP cations form molecular columns in the spaces between the chains. Although the dominant interaction of the molecules with their surroundings is electrostatic, their bonding are further enhanced by N-H…O and C-H…O hydrogen bonds.

Rietveld analysis of X-ray powder diffraction data was performed on SmBa4Cu3O8.5+δ, which was synthesized from precursors Sm2O3, BaO2, and CuO at 1000 °C in an oxygen atmosphere. SmBa4Cu3O8.5+δ has a cubic perovskite-related structure that is isostructural with YBa4Cu3O8.5+δ, and a doubled perovskite unit cell parameter of 8.177 90±0.000 04 Å.

X-ray powder diffraction data for the tetraphosphinic Si(CH2PPh2)4 silane are reported. Its crystal and molecular structures were determined by simulated annealing and full-profile Rietveld refinement methods. Si(CH2PPh2)4 was found to have tetragonal symmetry with P-421c space group. The lattice parameters were determined to be a=17.211(2) Å, c=7.553(1) Å, V=2237.5(5) Å3. The crystal structure was found to contain isolated Si(CH2PPh2)4 molecules. In each Si(CH2PPh2)4 molecule, the central Si atom was fixed at the −4 symmetric position bearing four CH2PPh2 branches. This environment was confirmed by 31P CP/MAS NMR measurements. Thermo-diffractometric measurements in the 20–120 °C range were also used to estimate the linear and volumetric thermal expansion coefficients (∂ ln V/∂T=1.8×10−4 K−1), typical for very “soft” materials.

A series of Dy2Co17−xGax polycrystalline samples with x from 0 to 7 were prepared by arc melting. X-ray powder diffraction analysis indicated that these compounds have the hexagonal Th2Ni17 structure for x≤3 and the rhombohedral Th2Zn17 structure for 3.5≤x≤7. The lattice parameters a and c increase linearly with the gallium content until x=5.3. With further increasing the gallium content x up to 7, the lattice parameter c slightly decreases, whereas the lattice parameter a increases more quickly than that for 0≤x≤5.3. The unit-cell volume shows an approximately linear increase of 6.1 Å3/Ga for 0≤x≤3.0 and 10.1 Å3/Ga for 3.5≤x≤7.0, respectively. Rietveld refinement of the Dy2Co11.7Ga5.3 compound reveals that the Ga atoms occupy all the 6c, 9d, 18f, and 18h sites and preferentially occupy the 6c site. The Curie temperature and the saturation magnetization of the rhombohedral Dy2Co17−xGax compounds decrease almost linearly with increasing Ga content.

The low-cycle fatigue behavior of a cobalt-based superalloy was studied in situ using neutron–diffraction experiments. The alloy exhibited stress-induced formation of a hexagonal-close-packed (hcp) phase within its parent face-centered-cubic (fcc) phase at ambient temperature under strain-controlled fatigue conditions with a total strain range, Δε=2.5%. The (101) hcp peak was first observed during the 12th fatigue cycle under the given conditions following a period during which no hcp phase was detected. Subsequently, the intensity of the hcp peaks increased as fatigue progressed. Furthermore, within a single fatigue cycle, the intensity of the (101) hcp peak decreased during the compression half-cycle and increased again when the specimen was subjected to a subsequent tensile strain. The result suggests that the fcc to hcp transformation is partially reversible within one fatigue cycle.

Diffraction data of calcite were collected using a conventional Bragg–Brentano diffractometer, which is a convenient, low-cost, and highly popular in-house instrument, and its crystal structure was refined by the Rietveld method. This paper shows how one treats preferred orientation and how different refinement strategies affect the accuracy of the result.

Si–SiC composite (reaction bonded SiC) with a submicron SiC microstructure (starting SiC particle size: 0.22 μm) was examined by XRD analysis to determine the amount and phase composition of the secondary SiC formed by the reaction between silicon and carbon during the sintering process. It was found that the secondary SiC has grown onto the original hexagonal α-SiC grains as well as into the porosity of the green body. An increase of 3C–SiC was found within the microstructure after infiltration (from 2.6 wt. % before infiltration to 8.8 wt. % after infiltration) whereas the 4H-ploytype content was reduced. This behavior may be explained by the very small original SiC grains which acted as seeds for disoriented SiC growth and were assumed to force the nonepitaxically deposition of secondary SiC. Solid state and fast transportation processes caused the observed transformation of the SiC. Examinations of the silicon source (infiltrant) after the infiltration procedure showed that most of the carbon was converted to SiC with cubic modification (3C stacking sequence)

X-ray fluorescence spectrometry (XRF) and micro-X-ray diffraction (μXRD) were used to analyze the composition of pigments on a pastel drawing, Special No. 32, by Georgia O’Keeffe. XRF analyses showed that, among other pigments present in the drawing, the red, orange, and yellow pigments may possibly be identified with lead- and chromium-based pigments: lead chromates, red and yellow lead oxides, and/or lead carbonates, plus calcium-based pastel fillers, such as whiting or gypsum. XRD examination of a sample removed from a dark mottled area of coral red pastel confirmed that this pigment layer, which is associated with a darkened appearance and high Pb:Cr ratios, matches the red lead oxide, minium (2PbO⋅PbO2).

The crystal structure of the tysonite-type superstructure of β-PrF3 has been studied by X-ray powder diffraction and high-energy electron diffraction from single crystals. The crystal data are: a = 7.0795(1) Å, c = 7.2380(2) Å, Z = 6, hexagonal system, space group (No. 165), ρcalc = 6.28 g cm−3. Atomic parameters and interatomic distances are presented from the final refinement with Rconv = 1.72%.

New layered bismuth oxides Bi2(BiCaNa)m−1NbmO3m+3(m=2-4) with the Aurivillius type phase were successfully synthesized. The structures of the compounds have been studied by X-ray powder diffraction and refined by the Rietveld method. Bi2.25Ca0.5Na0.25Nb2O9(m=2) has an orthorhombic crystal structure with lattice constants a=5.4478(1) Å;b=5.4770(2) Å;c=24.883(8) Å, space group A21am (No. 36). Bi2CaNaNb3O12 and Bi2.25Ca0.5Na1.25Nb3O12(m=3) are orthorhombic with Fmmm(No. 69) space group and the unit-cell parameters a=5.4473(7) Å, b=5.4770(3) Å, c=32.722(6) Å and a=5.4574(7) Å, b=5.4884 (3) Å, c=32.711(6) Å, respectively. The structure of Bi2CaNa2Nb4O15(m=4) was found to be orthorhombic with parameters a=5.4584(8) Å, b=5.4833(3) Å, c=40.534(1) Å and was refined in the space group A21am (No. 36).

Calibration of the prototype Planetary Instrument for X-ray Lithochemistry (PIXL) selected for Mars 2020 has commenced with an empirical derivation of the X-ray optic transmission profile. Through a straightforward method of dividing a measured “blank” spectrum over one calculated assuming no optic influence, a rudimentary profile was formed. A simple boxcar-smoothing algorithm was implemented to approximate the complete profile that was incorporated into PIQUANT. Use of this form of smoothing differs from the more conventional approach of using a parameter-based function to complete the profile. Comparison of element-specific correction factors, taken from a measurement of NIST SRM 610, was used to assess the accuracy of the new profile. Improvement in the low- to mid-energy portion of the data was apparent though the high-energy region diverged from unity, and thus, requires further refinement.

Crystal structure of the triclinic ternary phase Cr4(Al, Si)11 was investigated by full-profile Rietveld analysis of powder diffraction data. Four hundred eighty-four reflections were refined to a final RBragg value of 5.00%. Cr4(Al, Si)11 is isostructural to Mn4Al11. Silicon atoms enter into the structure by partially replacing aluminium on the Al(1) and Al(2) sites.

A Siemens D500 powder diffractometer has been modified to accommodate data collection and storage by an IBM microcomputer. The interface mechanism, described in detail, is simple, versatile and relatively low cost. The system performance is evaluated and further enhancements suggested.

Bafertisite, Ba(Fe, Mn)2Ti(Si2O7)O(OH, Cl)2, has been reported as belonging to three space groups, i.e., Pmmn, P21/m, and Cm. The samples of bafertisite from the original locality Bayan Obo, Inner Mongolia, and from Jiangsu Province, China, were reinvestigated by X-ray methods. On the basis of single-crystal photographs, Pmmn could be ruled out and the relationship between a subcell in P21/m and the true cell in Cm deduced. The transformation matrix from the subcell to the true cell is 002/02¯0/101¯. Using the X-ray powder data, the refined true unit cell parameters in space group Cm are: a=10.612(3), b=13.637(7), c=12.464(2) Å, β=119.49(2)° for Bayan Obo sample, and a=10.633(6), b=13.67(1), c=12.465(5) Å, β=119.55(4)° for the Jiangsu sample. The 00l-reflections, which are rather prominent due to preferred orientation, can only be explained by our new unit cell.

X-ray fluorescence (XRF) is a well-established method for quantitative elemental analysis. For accurate quantification, secondary excitation has to be taken into account. In this paper, the secondary excitation process was discussed for analysis by confocal micro-XRF. Experimental depth profiles were shown for a layered sample of Co and Cu. An additional peak was observed in the depth profile of Co, and it was explained by secondary excitation process. Additionally, a Mosaic model was proposed for quantification of confocal micro- XRF analysis.